It is strong evidence to those who do not understand what the numbers mean that Corsi is a fraud when I posted the top 20 players in the 2013 season by Raw Corsi and Justin Williams of the Los Angeles Kings lead the NHL. He posted a +339 difference is shots attempted by his team in 5 on 5 situations than his opponents took. That must be wrong because nobody claims Williams is the best player in the NHL. In fact nobody seriously considers him an All Star player. Therefore those who do not understand Corsi think it is all disproven and the idea should go away never to be heard from again. There is some kind of false idea that posting the leader in some statistical area has to produce the name of a player who is at least arguably the top player in the NHL or else that stat proves nothing. That idea is beyond silly if you think about it for any longer than a second.

In fact the case of Justin Williams posting a top Corsi is not new. I wrote about him last year here when he posted the 4th best raw Corsi in the league in 2011/12 and he posted the 17th best raw Corsi in 2010/11. Thus it is not a fluke that Williams posts a top Corsi. He is a good example of the context dependent information that comes from Corsi ratings and the fact that analysis is necessary to raw numbers.

The easiest example of a context dependent conclusion is that Williams gets an ever improving raw Corsi rating as he plays on an ever improving team. Team context is a big part of any Corsi number. A player on a good team should post a better Corsi rating than one on a bad team. Of course Corsi ratings cannot be directly compared between different teams. In fact they cannot be directly compared between players on the same team. It would be a silly conclusion that Justin Williams is the best player on the Los Angeles Kings because he has the best Corsi on the team. It doesn't pass the "eye test" where I watch hockey and run any conclusions the numbers may show past what I see with my eyes.

Justin Williams is a good offensive player. He scored 33 points in 48 games last season, which placed him in a tie for second among Kings scorers. he is coming off back to back 59 and 57 point seasons. He can score and is the best pure winger on the Los Angeles Kings so he gets to play with good centremen - most often Anze Kopitar. Given his skillset, he plays offensive situations as exclusively as possible. He is not used in defensive situations, such as those against top opposition or when the zone starts in his own defensive zone. Thus he is removed from situations where he might be more likely to get a negative Corsi as the other team would possess the puck and take shots. This offensive usage is one that improves his Corsi and helps contribute to his lead leading numbers. When this context is subtracted from his play, Justin Williams falls back into the pack as one might expect We shall see that in the future.

Justin Williams is the player who has the best team puck possession record while he is on the ice at five on five situations in the NHL in 2013. That is an interesting result. That result shows that Williams is a good offensive player, but it does a better job of showing that he plays on a good team with top linemates and avoids defensive situations.